Re: Undo/Redo

Hi,
I need to develop Undo/Redo Function in my application. I'm using a manual coded annotation environment, not the automated one. In automated env I see the way, but in manual coded way?

Thanks.

P.S.: I use LT 14.5 in Vb.NET

There is no built-in Undo/Redo feature when you use non-automated Annotations. One way to implement them yourself is to take a snapshot of the annotations before every change using the AnnCodecs.Save Method (for example to a memory stream). When the user wants to undo a step, you can use the AnnCodecs.Load method to retrieve the previous state.

Hi Expert,

I'm using LeadTools 14.5 in my application with automated annotations. I found that there is no support for Redo, though there is a support for Undo.

Will you please guide me how to implement Redo functionality? Actually, I'm not getting the recently undone HANNOBJECT. I thought of using the recently undone HANNOBJECT to insert again into the container.

Hope to get a positive and valuable reply soon.

~Vijay

The easiest way to do it would be to Save and load annotation files.  Depending on your LEADTOOLS interface, the function calls will be a little different, but the basic idea is this:

1. Just before calling Undo, save an annotation file to a temporary disk location.  You should do this each time you wish to be able to track undos so that ou can redo the action.  For example, if you only want to be able to redo up to the last 10 undos, you should create up to 10 annotation files.
2. If you decide you want to redo an action, all you have to do is delete all the annotations currently on your container and then load the annotation file corresponding to the latest undo action.
3. Whenever you redo, you will probably want to delete the annotation file you used to "redo" as well as delete them all once your application is done running.